Build a rocket, make a bottle invisible, polarize light, silence a blaring radio. The experiments in this sample chapter demonstrate some of the basic laws of physics, and require only household items to accomplish.

This chapter is from the book

Rockets with Chemical and Air Propulsion

Let's build a cool rocket and its launch platform
from scratch.

A. Chemical Propulsion

Step By Step

Supplies

vinegar

baking soda

empty film canister with lid

construction paper

superglue

masking tape

Put a small amount of baking soda and some vinegar
(figure out for yourself the proportions that work
best) in the film canister and cover it quickly.
The lid of the film canister is the bottom end of
your rocket. Stand back and get ready for blast-off!
You can improve your rocket by adding a conic nose
and fins made of construction paper to it, as done
in the next model (air propulsion).

WARNING

Be sure you choose a launch site
that will not be damaged by the vinegar and baking
soda!

A Step Further

There is a slightly more sophisticated way to engineer
your rocket. Mix the baking soda with water to form
a paste that will stick inside the lid of the film
canister even when you hold it upside down and put
it on the canister. Calculate the right amounts,
spread the baking soda inside the lid, and place
the vinegar in the canister. Put the lid on the canister,
keeping the canister upright. When you are ready
for launch, turn the canister upside down and place
it on the launch site. Watch it go!

Can you think of other ways to engineer a vinegar
and baking soda rocket?

Fun Facts

In the case of the chemical propulsion, vinegar,
an acid, and baking soda (sodium bicarbonate) mixed
together produce carbonic acid, which quickly decomposes
into carbon dioxide (CO2) and water. As
the CO2 expands, it makes the rocket (canister)
move up. The rocket is hit by the CO2 molecules
moving up and, in turn, it kicks them back. It is
the action = reaction principle at work.

B. Air Propulsion H

Step By Step

Supplies

construction paper

3.3 ft (1 m) piece of ridged hose

9 in (22 cm) piece of PVC pipe in which the
hose can be fitted tightly

With a hacksaw (or other saw), cut off a piece of
the wood stick. Attach the stick laterally to the
base with two nails, as shown in the figure. Insert
one end of the hose into the tube until it reaches
the tube's end. Drill a hole all the way through
from one side of the tube to the other to pass the
screw. Use the screw to fasten the tube to the wood
stick. Insert the other end of the hose into the
bottle (if necessary, use masking tape around the
tube's ends to keep the hose tightly fitted).

The Rocket

Make an 8 in (20 cm) long cylinder out of construction
paper, which fits tightly in the PVC pipe. Draw on
the construction paper a 1 1/4 to 2 in (3 to 5 cm)
radius semicircle, using the disk as a guide, or
use the drawing compass. Cut out the semicircle and
make a cone out of it that fits the cylinder. Attach
the cone to the top of the cylinder with masking
tape. Alternatively, you can use a Styrofoam ball
as the nose of the rocket. Just fit it in the top
end of the cylinder (using glue or masking tape to
fasten it to the body of the rocket). Cut out three
rectangular triangles with roughly 1 3/8 in (3.5
cm) base and 2 in (5 cm) height for the three fins.
Fold 1/4 in (0.5 cm) of the border of the triangles
(see figure) and attach them to the rocket's
body at the places indicated. The fins can be positioned
either vertically or slightly tilted (around 20º).
To launch the rocket, just put the bottle on the
ground and stomp on it with one foot. You can try
different rocket designs to see which achieves the
highest point. You can also tilt the platform and
discover at which angle the rocket reaches the maximum
distance on the ground. After each launching, the
plastic bottle deforms. To restore it, you have to
blow through the top end of the PVC pipe. Eventually,
you will have to replace the bottle and make a new
rocket.

The air flow kicks the rocket up, and the rocket
in its turn kicks the air back. This is just the
action = reaction principle at work. Can you recognize
here the same principle of the previous rockets?
The fins of the rocket also play an important role,
as they do for sharks and other fish. When the fins
are tilted, they make the rocket spin around its
axis. When you ride a bicycle, you don't fall
because the spinning wheels give it a special stability.
(See Experiment 35, "The Bicycle's Trick")
The same holds for the turbines of the jet engines
of an airplane. What about the rocket?